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CVE-2026-87018

CVE-2026-87018 · undici vulnerable to Denial of Service via TLS 1.2 certificate-changing renegotiation

This page contains facts from public vulnerability sources. Check the original advisory before updating.

undici is an HTTP client library for Node.js. In versions 4.2.1 through 6.29.0, 7.0.0 through 7.30.0, and 8.0.0 through 8.12.1, the client process crashes when a TLS 1.2 server renegotiates after the connection is established and presents a different, CA-trusted certificate whose hostname does not match the requested host. Node.js re-runs hostname verification on the renegotiated handshake and destroys the socket with a certificate-altname error, but undici's established-socket error handler asserted that this error code could never occur, so the peer-controlled error became an uncaught assertion that terminates the Node.js process, affecting both the HTTP/1.1 and HTTP/2 paths. A malicious or compromised HTTPS endpoint reached through undici or the global fetch() can crash the client with a single server-initiated renegotiation, taking down all in-flight requests and background work in the process, and exploitation needs no CA compromise because the attacker controls the endpoint and can present two ordinary valid certificates. Only TLS 1.2 is affected, since TLS 1.3 does not support renegotiation. The issue is fixed in undici 6.29.1, 7.30.1, and 8.12.2, and users should upgrade to one of those versions or later. As a workaround, restrict outbound connections to TLS 1.3 so renegotiation cannot occur, when the target endpoints support it.

CVSS 7.5 · High · EPSS 0.2% · Fix available

Published
Updated

Stack: system

Affected products and versions

  • undici

    Versions
    • ≥ 4.2.1, < 6.29.1: Affected (semver)
    • 6.29.1: Not affected (semver)
    • ≥ 7.0.0, < 7.30.1: Affected (semver)
    • 7.30.1: Not affected (semver)
    • ≥ 8.0.0, < 8.12.2: Affected (semver)
    • 8.12.2: Not affected (semver)

    Update to 6.29.1; Update to 7.30.1; Update to 8.12.2

  • node-undici Debian:12

    Versions
    • 5.15.0+dfsg1+~cs20.10.9.3-1
    • 5.15.0+dfsg1+~cs20.10.9.3-1+deb12u1
    • 5.15.0+dfsg1+~cs20.10.9.3-1+deb12u2
    • 5.15.0+dfsg1+~cs20.10.9.3-1+deb12u3
    • 5.15.0+dfsg1+~cs20.10.9.3-1+deb12u4
    • 5.19.1+dfsg1+~cs20.10.9.5-1
    • 5.19.1+dfsg1+~cs20.10.9.5-2
    • 5.22.1+dfsg1+~cs20.10.10.2-1
    • 5.26.3+dfsg1+~cs23.10.12-1
    • 5.26.3+dfsg1+~cs23.10.12-2
    • 5.26.3+dfsg1+~cs23.10.12-3
    • 5.28.0+dfsg1+~cs23.11.12.3-1
    • 5.28.0+dfsg1+~cs23.11.12.3-2
    • 5.28.2+dfsg1+~cs23.11.12.3-1
    • 5.28.2+dfsg1+~cs23.11.12.3-2
    • 5.28.2+dfsg1+~cs23.11.12.3-3
    • 5.28.2+dfsg1+~cs23.11.12.3-4
    • 5.28.2+dfsg1+~cs23.11.12.3-5
    • 5.28.2+dfsg1+~cs23.11.12.3-6
    • 5.28.4+dfsg1+~cs23.12.11-1
    • 5.28.4+dfsg1+~cs23.12.11-2
    • 7.1.0+dfsg1+~cs24.12.10-1
    • 7.15.0+dfsg+~cs3.2.0-1
    • 7.15.0+dfsg+~cs3.2.0-3
    • 7.16.0+dfsg+~cs3.2.0-1
    • 7.16.0+dfsg+~cs3.2.0-2
    • 7.18.2+dfsg+~cs3.2.0-1
    • 7.2.3+dfsg1+~cs24.12.11-1
    • 7.2.3+dfsg1+~cs24.12.11-2
    • 7.24.5+dfsg+~cs3.2.0-1
    • 7.24.6+dfsg+~cs3.2.0-1
    • 7.24.6+dfsg+~cs3.2.0-2
    • 7.24.6+dfsg+~cs3.2.0-3
    • 7.3.0+dfsg1+~cs24.12.11-1
    • 7.3.0+dfsg1+~cs24.12.11-2
    • 8.10.2+dfsg+~cs3.2.2-1
    • 8.12.1+dfsg+~cs3.2.3-1
    • 8.12.2+dfsg+~cs3.2.3-1
    • 8.12.2+dfsg+~cs3.2.3-2
    • 8.5.0+dfsg+~cs3.2.0-1
    • 8.5.0+dfsg+~cs3.2.0-2
    • 8.5.0+dfsg+~cs3.2.0-3
    • 8.9.0+dfsg+~cs3.2.0-1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • node-undici Debian:13

    Versions
    • 7.15.0+dfsg+~cs3.2.0-1
    • 7.15.0+dfsg+~cs3.2.0-3
    • 7.16.0+dfsg+~cs3.2.0-1
    • 7.16.0+dfsg+~cs3.2.0-2
    • 7.18.2+dfsg+~cs3.2.0-1
    • 7.24.5+dfsg+~cs3.2.0-1
    • 7.24.6+dfsg+~cs3.2.0-1
    • 7.24.6+dfsg+~cs3.2.0-2
    • 7.24.6+dfsg+~cs3.2.0-3
    • 7.3.0+dfsg1+~cs24.12.11-1
    • 7.3.0+dfsg1+~cs24.12.11-2
    • 8.10.2+dfsg+~cs3.2.2-1
    • 8.12.1+dfsg+~cs3.2.3-1
    • 8.12.2+dfsg+~cs3.2.3-1
    • 8.12.2+dfsg+~cs3.2.3-2
    • 8.5.0+dfsg+~cs3.2.0-1
    • 8.5.0+dfsg+~cs3.2.0-2
    • 8.5.0+dfsg+~cs3.2.0-3
    • 8.9.0+dfsg+~cs3.2.0-1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • node-undici Debian:14

    Versions
    • 7.15.0+dfsg+~cs3.2.0-1
    • 7.15.0+dfsg+~cs3.2.0-3
    • 7.16.0+dfsg+~cs3.2.0-1
    • 7.16.0+dfsg+~cs3.2.0-2
    • 7.18.2+dfsg+~cs3.2.0-1
    • 7.24.5+dfsg+~cs3.2.0-1
    • 7.24.6+dfsg+~cs3.2.0-1
    • 7.24.6+dfsg+~cs3.2.0-2
    • 7.24.6+dfsg+~cs3.2.0-3
    • 7.3.0+dfsg1+~cs24.12.11-1
    • 7.3.0+dfsg1+~cs24.12.11-2
    • 8.10.2+dfsg+~cs3.2.2-1
    • 8.12.1+dfsg+~cs3.2.3-1
    • 8.12.2+dfsg+~cs3.2.3-1
    • 8.12.2+dfsg+~cs3.2.3-2
    • 8.5.0+dfsg+~cs3.2.0-1
    • 8.5.0+dfsg+~cs3.2.0-2
    • 8.5.0+dfsg+~cs3.2.0-3
    • 8.9.0+dfsg+~cs3.2.0-1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • node-undici Ubuntu:24.04:LTS

    Versions
    • 5.22.1+dfsg1+~cs20.10.10.2-1ubuntu1
    • 5.26.3+dfsg1+~cs23.10.12-2
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • node-undici Ubuntu:26.10

    Versions
    • 7.18.2+dfsg+~cs3.2.0-1build1
    • 7.24.6+dfsg+~cs3.2.0-3
    • 8.5.0+dfsg+~cs3.2.0-2
    • 8.5.0+dfsg+~cs3.2.0-3
    • 8.9.0+dfsg+~cs3.2.0-1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • node-undici Ubuntu:26.04:LTS

    Versions
    • 7.3.0+dfsg1+~cs24.12.11-2
    • 7.16.0+dfsg+~cs3.2.0-2
    • 7.18.2+dfsg+~cs3.2.0-1
    • 7.18.2+dfsg+~cs3.2.0-1build1
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

Original sources

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